Effect of the Engineered Indole Pathway on Accumulation of Phenolic Compounds in Catharanthus roseus Hairy Roots

• Published in: Biotechnology progress Vol. 23; no. 2; pp. 327 - 332
• Main Authors: Chung, I.M, Hong, S.B, Peebles, C.A.M, Kim, J.A, San, K.Y
• Format: Journal Article
• Language: English
• Published: USA American Chemical Society 01-03-2007; American Institute of Chemical Engineers
• Subjects: anthranilate synthase; Anthranilate Synthase - genetics; Anthranilate Synthase - metabolism; Biological and medical sciences; biosynthesis; Biotechnology; catechin; Catharanthus - genetics; Catharanthus - metabolism; Catharanthus roseus; Fundamental and applied biological sciences. Psychology; gene transfer; genetic transformation; hairy roots; Indoles - metabolism; phenolic compounds; Phenols - pharmacokinetics; Plant Roots - genetics; Plant Roots - metabolism; Plants, Genetically Modified - physiology; Protein Engineering - methods; Rhizobium rhizogenes; roots; Signal Transduction - physiology; transgenic plants; Tryptophan - genetics; Tryptophan - metabolism; Apocynaceae; Hairy root; Dicotyledones; Indole; Angiospermae; Phenols; Spermatophyta; Catharanthus roseus; Accumulation
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp060258e

Catharanthus roseus has been well‐known to contain indole alkaloids effective for treatment of diverse cancers. We examined the intracellular accumulation profiles of phenolic compounds in response to ectopic overexpression of tryptophan feedback‐resistant anthranilate synthase holoenzyme (ASαβ) in C. roseus hairy roots. Among 13 phenolic compounds measured, 6 phenolic compounds were detected in late exponential phase ASαβ hairy roots. Uninduced and induced ASαβ hairy roots accumulated up to 1.2 and 4.5 mg/g DW over a 72‐h period, respectively. Upon induction, in parallel with a rapid increase in tryptophan in the first 48 h, accumulation of phenolic compounds tended to increase to a maximum level (4.5 mg/g DW) at 48 h, after which phenolic levels decreased back to the uninduced level by 72 h. Naringin was a predominant form that comprised about 72% and 36% of the total content of phenolic compounds in the uninduced and induced lines, respectively. Upon induction, accumulation of catechin drastically increased with the highest level (3.6 mg/g) occurring at 48 h, whereas that of all others except for salicylic acid showed no statistical difference. Catechin is a final product of the flavonoid pathway, and thus metabolic flux into this pathway is transiently increased by overexpression of AS. Like catechin, salicylic acid is very sensitive to induction as it began to increase to 5‐fold within 4 h of induction, but unlike catechin, no significant accumulation of salicylic acid was noted after 4 h of induction. The results suggest differential regulation of this particular biosynthesis branch within the phenolic pathway.